Synseeds for Propagation and Preservation of Ferocactus peninsulae (Cactaceae) and Xeromorphic Adaptations of Seedlings

Abstract

Ferocactus peninsulae (A.A.Weber) Britton & Rose (Cactaceae) has great potential for commercial exploitation by the horticulture industry. It is difficult to propagate vegetatively, and we investigated novel propagation methods. The objectives were to optimize the organic supplements in nutrient medium for seed germination, synthetic seed (synseeds) production, and in vitro and ex vitro retrieval of plantlets after 12 months of cold storage. Seeds were germinated on different strengths of Murashige and Skoog's (MS) nutrient media under variable temperatures. Full strength MS medium augmented with 2.0 mg L-1 6-benzylaminopu-rine (BAP) incubated at 24°C temperature was optimum for seed germination with 98% maximum response. Synseeds were produced from the eight-week-old in vitro germinated seedlings using 2% sodium alginate and 100 mM calcium chloride solutions. These were cold stored under low temperature (- 4°C) for 12 months. The highest percentage (92%) of synseed germination and seedling growth (4.2 cm shoot with 7.1 cm root) was attained on MS medium fortified with 1.0 mg L-1 BAP after 12 wk. About 80.5% of cold stored synseeds germinated under greenhouse conditions (ex vitro) on Soilrite® with healthy shoots (3.7 cm length) and well-developed roots (4.0 cm) within 12 wk. No apparent differences were observed between in vitro and ex vitro raised seedlings. These results would reveal the short-term cold preservation of germplasm of barrel cactus, and it is also effective in in vitro and ex vitro germination. A comparative micro-morpho-anatomical study of in vitro and acclimatized seedlings of F. peninsulae was conducted to understand the xeromorphic adaptations of cacti with reference to stomata, spines and internal anatomy peculiar to the arid environments.